/in/foo.cc: In function 'bool CheckReverse(Date)':
/in/foo.cc:192:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int i = 0; i < solo._ori.length(); i++) {
                    ~~^~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'void DisplayDateList()':
/in/foo.cc:254:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int i = 0; i < _myList.size(); i++) {
                    ~~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'void DisplayIntList(std::vector<int>)':
/in/foo.cc:353:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < theList.size(); i++) {
                  ~~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int GenFitNum(int)':
/in/foo.cc:394:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < bitList.size(); i++) {
                  ~~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int CalcDays(Date)':
/in/foo.cc:249:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^